Since I live in America now, I no longer use SK Telecom, but watching this 'SIM information leak incident' felt like it was happening in another country.

On April 19, 2025, a shocking incident occurred at SK Telecom, a leading telecommunications company in Korea. It was reported that a hacker infiltrated SK Telecom's authentication server, leaking numerous users' SIM information (IMSI, IMEI, authentication keys, etc.). Although they clarified that it was not traditional personal information like resident registration numbers or financial information... to be honest, that's not what matters right now.

With just that information, a hacker can clone the victim's phone number, disrupt communications, log into financial apps, authenticate via text messages, and even steal virtual asset accounts. Many people in America have also suffered such damages. This method is called SIM swapping, and it should be seen as 'hacking into an entire private life' rather than just a simple data leak.

In fact, a few years ago, famous influencers and even the Twitter CEO in America were attacked by this. In Korea, numerous SIM swapping victims were confirmed a few years ago, with damages reaching millions to tens of millions of won. Yet, SK Telecom is not even properly disclosing the details of this incident.

The scarier part is that no one knows exactly what happened. How the hacker infiltrated, which server the information was leaked from, whether it was encrypted, how internal employee permissions were managed... even basic information like this is missing.

They just keep repeating, "We have taken additional measures" and "We have strengthened monitoring," while users are left in the dark. Right now, someone could be unknowingly having their phone turned off due to a hacked SIM, and their bank account or coin wallet could be getting emptied.

Living in America, I have seen similar incidents several times. Once, someone I know had their text message authentication intercepted, and a few days later, their bank account was emptied without them knowing. So, I am very sensitive about phone security. I set a password on my SIM, activated phone theft mode, and made sure that my carrier requires direct verification for SIM changes.

However, I felt that Korea is still not at that level. Since changing SIMs is relatively simple and basic security settings are often low, the damage can be greater when such leaks occur.

For those in Korea, if you are using SK Telecom, please make sure to check your SIM security. Set a password on your SIM, and subscribe to additional services like 'blocking overseas networks.' If you feel uneasy, it's best to just switch to a new SIM. Trying to save money can lead to significant losses quickly.

This is not just an issue for SK Telecom. It is a case that shows how vulnerable telecommunications security systems can be, and it indicates that telecommunications companies worldwide need to respond at a much higher level and provide transparent disclosures.

Whether it's SK Telecom or another carrier, we are the users. If we just brush off such incidents with "that could happen," we could be the next victims. I believe this incident should be fully disclosed, those responsible should be held accountable, and systems and regulations should change to prevent such leaks from happening again.

I am not a customer of SK Telecom, but this issue concerns all digital users.

It's the same in Korea, America, or anywhere else.